1. Field of the Invention
The present invention relates to a high-frequency module that transmits and receives a plurality of communication signals using a common antenna.
2. Description of the Related Art
In the past, various kinds of high-frequency modules have been designed to transmit and receive a plurality of communication signals using a common antenna, each of the plural communication signals utilizing a different frequency band. For example, such a high-frequency module is described in Japanese Unexamined Patent Application Publication No. 2008-10995.
The high-frequency module described in Japanese Unexamined Patent Application Publication No. 2008-10995 includes a laminated body including a predetermined inner layer electrode pattern, and a switch element and an SAW filter that are mounted in the upper surface of the laminated body. The switch element includes a common terminal to be connected to an antenna and individual terminals each of which is to be connected to a transmission circuit or a reception circuit, used for a plurality of communication signals. On the basis of a control signal, the switch element connects one of the individual terminals to the common terminal, and hence switches to and connects one of the transmission circuit and the reception circuit to the antenna.
In the case of such a high-frequency module utilizing the laminated body, a circuit configuration other than mounted components such as the switch element and the SAW filter is realized using inner layer electrode patterns formed within the laminated body.
However, when the high-frequency module is downsized, electromagnetic field coupling occurs between circuit elements realized by these inner layer electrode patterns. For example, a plurality of inductors on a transmission path transmitting one communication signal are electromagnetic-field-coupled to one another, an inductor of a circuit on the common terminal side of the switch element is electromagnetic-field-coupled to an inductor of a circuit on the individual terminal side of the switch element, or inductors individually connected onto a plurality of different transmission paths are electromagnetic-field-coupled to one another. In such a case, it may be hard to obtain a desired transmission characteristic. For example, an inductor of a low pass filter used for a second harmonic wave and an inductor of a low pass filter used for a third harmonic wave, connected in series onto one transmission circuit, are electromagnetic-field-coupled to each other, and hence it may be hard to fully attenuate the second harmonic wave and the third harmonic wave of a communication signal transmitted through the corresponding transmission circuit. In addition, an inductor used for an antenna side matching circuit is electromagnetic-field-coupled to an inductor of a low pass filter used for a second harmonic wave or an inductor of a low pass filter used for a third harmonic wave, connected in series to a transmission circuit, and hence it may be hard to fully attenuate the harmonic wave of a communication signal transmitted through the corresponding transmission circuit.